In aquaculture to get a high production is conditioned by awareness and keeping of an unaltered health condition of the biological material. To be aware of the health condition of the biological material in a fish farm allows us to establish the preventive measures required to prevent spreading of a disease and the treatment to be applied in case that a mass disease occurs. The level of the total protein in serum is, first of all, a synthetically indicator of the nutritional condition of the organism, presenting, at the same time, ample qualitative and quantitative variations depending on species, age, sex, stage of sexual maturity, water temperature and especially in correlation with the health condition of fish. Modification in value of the total protein point out some metabolic perturbations in fish body.